There is controversy regarding soy protein for men. It seems soy protein contains compounds that are estrogen-like, and many men are reluctant to eat a lot of soy because of this. Resent research may put some of these fears to rest, so don’t rule out this great source of protein just yet.Background
Soy protein contains isoflavones, which are compounds that act like estrogen in the human body. Soy protein is also listed as the only complete protein that is plant based, so if you are vegetarian or vegan, or just cutting down on meats, this is the only substitute that gives all the essential amino acids. So the controversy stems from the need to risk things like man boobs to be able to get proper nutrition without eating animal based protein.
Scientific studies offer mixed results regarding isoflavones. A study this year in “Toxicology in Vitro” says that there is a feminizing affect on developing male fetuses. However, last year in “Fertility and Sterility” a study showed that at typical levels of soy consumption do not affect sperm, free testosterone, or total testosterone levels in developing males. Some experts suggest that the disparity of results comes from the fact that rodent test subject metabolize isoflavones differently than humans and the fact that in test studies, the rodents are fed much higher levels of the compounds than would normally be consumed.
Plant-based proteins such as soy do not contain saturated fats or cholesterol, so substituting some soy for high-fat animal protein can lead to a healthier heart. Other researchers have shown that consumptio of soy protein also lowers bad cholesterol levels.
Many of the sports supplement products taken by endurance athletes and men doing strength training contain soy protein. The American Dietetic Association reports that high quality plant proteins such as casein, whey, or soy can help enchance muscle gain from exercise, as well as maintenance and repair of muscle mass.
Soy is a good source of protein, but it should be taken in moderation, just like everything else. A normal diet that includes soy protein will not cause a man to need to shop for bras, but it will deliver numerous health benefits.